<template>
    <div>
        <router-link tag="div" 
        to="/" 
        class="header-abs"
        v-show="showAbs"><div class="iconfont header-abs-back">&#xe608;</div></router-link>
        <div class="header-fixed" 
        v-show="!showAbs"
        :style="opacityStyle">
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe608;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>

<script>
export default {
   name: 'DetailHeader',
   data () {
       return {
           showAbs: 'true',
           opacityStyle: {
               opacityStyle:0
           }
       }
   },
   methods: {
       handleScroll() {
           const top = document.documentElement.scrollTop || document.body.scrollTop || window.pageYOffset
           if(top>60) {
               let opacity = top / 140
               opacity = opacity > 1 ? 1 : opacity
               this.opacityStyle = {
                   opacity
               }
               this.showAbs = false
           }else {
               this.showAbs = true
           }
       }
   },
   mounted () {
       window.addEventListener('scroll',this.handleScroll)
   },
   destroyed () {
       window.removeEventListener('scroll',this.handleScroll)
   }
} 
</script>

<style lang="stylus" scoped>
    @import '~styles/varibles.styl'
    .header-abs
        position absolute
        top .2rem
        left 0.2rem
        width .8rem
        height .8rem
        line-height .8rem
        text-align center
        border-radius  .4rem
        background rgba(0,0,0,0.8)
        .header-abs-back
            color #fff
            font-size .4rem
    .header-fixed
        z-index 2
        position :fixed
        top 0
        right 0
        left 0
        overflow :hidden
        line-height :$headerHeight
        height :$headerHeight
        background :$bgColor        
        color:#fff
        text-align :center
        font-size:.32rem
        .header-fixed-back
            width 0.64rem
            text-align :center
            font-size:.4rem
            position :absolute
            top:0
            left :0
            color:#fff
</style>